Why do I do what I do?

The Curiosity rover is currently trundling its way across the surface of Mars in a quest to understand if Mars was ever able to support life and perhaps even detect evidence of past life. We’ve come a long way from fearing an attack from a hostile Martian civilisation. The Earth is at no risk from Martian rockets, heat rays or tripods. Mars, like our other nearest Solar System neighbour Venus, is a barren world devoid of any life. Why is the Earth the way it is and not more like Mars or Venus?

Photo: JPL / NASA

Prior to joining the Institute for Complex Systems Simulation at the University of Southampton I thought about this question rather a lot. It was a central part of my previous job as a member of the Helmholtz Alliance funded Planetary Evolution & Life project that I worked on at the Max Planck Institute for Biogeochemistry in Jena.

But my interest in this question predates my time in Germany. Continue reading

Cafe Scientific August 13th

I will be giving a Cafe Scientific talk at the Southwestern Arms, Southampton on Monday 13th August. I think things kick off around 7pm. Perhaps it depends on how much people have been drinking! I’m going to be talking about peak phosphorus and so will include some material from a previous post.

Come along and find out if I got round to producing more than a title slide.

So you want to do a PhD?

That’s great. Perhaps you would be interested in me supervising you? If so, you have impeccable taste. In any event let’s talk some more. Being paid to spend several years researching something in today’s economic environment is an amazing opportunity. Competition for PhD places can be incredibly fierce. If you are successful and not only get a position but a fully funded position then congratulations! I’m going to assume that you want to do a PhD in order to end up working in academia. If not then some/most of the following will not be of relevance, but perhaps still of interest. And most importantly, I’m going to assume that notwithstanding what I just said, you are well aware of the arguments for why doing a PhD isn’t a very good idea at all. You’re not? Ah.

Continue reading

A life of science

How is this not a good talk?

  • Reads from a script
  • Wears a hat that shades his eyes
  • Stiff even a little stilted delivery

And none of that matters. All the emphasis on polish and pitch and engagement and audio/visual presentation is irrelevant. It’s what he says that makes this a riveting talk. And I would hazard a guess that even if you strongly disagree with Hansen (and quite a few do) you would still find the talk riveting because he quickly focusses in on what the issue of climate change is about: to what extent are we affecting the Earth’s climate and what are the consequences to us and future generations?

Hansen is someone worth listening to because he has largely framed this debate (in the USA at least). He’s got a very interesting perspective: a life of science and reflection on what he has learnt and how that informs what he should do with the rest of his life.

Just what is global warming anyway?


Given the amount of news and media coverage about global warming you may have suspected that asking ‘what is global warming?’ was a bit of a stupid question. In the first instance it’s worth remembering that there are no stupid questions only stupid answers. But even ignoring that, ‘what is global warming?’ isn’t a stupid question. In fact it’s a very good one. Why?

Because listening to someone give an answer to the question ‘what is global warming?’ can tell you something interesting about that person. And perhaps people in general. Continue reading

Exponential energy

Here’s a remarkable fact.

In the years since 1990, our global civilisation used more energy than had been used in the previous several hundred thousand years, possibly since modern humans first evolved.

No, really. All the energy extracted by burning wood, coal, gas, oil and obtained from wind, solar, hydro and nuclear fission up to 1990. That same amount of energy used again plus a bit more in a little over 20 years.

How on Earth is that possible? To begin to answer that, we need to acknowledge that we are living in a period of quite incredible change. Yet this rate of change is something that we have gotten used to. Indeed, it was something that we were born into: a period of exponential growth. What does this exponential growth in energy look like? Something like this:

Continue reading


I had a slinky as a child and loved it. Initially because if you stretched it out a little bit and peered inside, it looked similar to this (alas no Tom Baker would appear at the other end). And then because it walked down stairs. All by itself. How did it do that? In that respect, a slinky is a fantastic tool for understanding physics. What is going on in a slinky that makes it able to walk down stairs or in the above instance a treadmill? Or perhaps a simpler question: what happens if you hold a slinky up so that its coils stretch down to just above the ground and then drop it? Continue reading

The intergenerational ponzi scheme

A ponzi scheme is a classic scam that despite being guaranteed to collapse continues to work and leave people penniless. It goes something like this. John tells Jane that he has a fantastic money making opportunity. If Jane invests she will get an annual return on that investment of 20%. Wow! Jane invests and sure enough next year she gets a payment of 20% of her original investment. Other people hear about her success and sign up. Soon John has many investors and a large amount of money in circulation. But none of that money was ever invested.

The second person that signed up to John’s scheme was Jack. John simply took 20% of Jack’s money and gave it to Jane. The rest he pocketed (and most probably promptly spent). Just like he pocketed Jane’s money. Of the third person’s money, John took 20% for Jane and 20% for Jack. The fourth person’s money paid the 20% of the first three. And so on, until John is unable to recruit enough new people to pay the returns of the current list of ‘clients’. There’s a short delay during which John avoids calls, perhaps changes address and if he’s sensible hires a good lawyer (with whatever money is left). Then the whole system collapses in on itself. Well, that’s the basics. Real life ponzi schemes can be much more complicated than that. But they all work on the same principles. Why they work, why people get sucked in and lose perhaps everything they have, are very interesting questions. Questions that get asked quite a lot since Bernie Madoff. If you rip people off to the tune of $18 billion dollars I guess that will make the news for some time. Continue reading

What is a complex system?

It’s a reasonable question. If I tell you that I work at the Institute for Complex Systems Simulation, then you may ask what is a complex system. I don’t think there is a definitive answer (so it’s pretty mean of us to ask PhD candidates this in their interview). I would say it’s a perspective or an approach to systems that traditionally have been hard to understand. Here, let me show you what I mean (this really works well full screen and with the sound up):

That is a complex system in which the interaction of individuals (birds) that follow three simple rules (try not to get too far away from your neighbours, but don’t get too close and try to go in the same general direction) can produce emergent behaviour that would not be predicted by analysing those simple rules alone. It also happens to be incredibly beautiful and captures a central element of what we can find so awe inspiring about nature. Much like biological evolution, a complex system seems to be able to continually generate complicated, interacting, dynamical patterns. In fact, the evolution of life on Earth, the process that produced hummingbirds and whales, worms and giant redwoods may be understood as a planetary scale complex system. Continue reading